Many projection systems, such as digital light projectors (DLPs), utilize a white light and a sequential color filter to produce different colors. The color filter, such as a color filter wheel, typically includes segments for each of the primary colors such as red, blue, and green, and spins at a predetermined rate as the white light is projected onto the color filter wheel to produce colored light corresponding to the colors of the color filter wheel. The colored light is projected onto a viewing screen to form an image.
The ratios between the red light, the green light, and the blue light of the colored lights are adjusted to change the color temperature of the image. Different color temperatures can give out different visual perceptions. For example, people tend to harbor a warm feeling when viewing objects in a low color temperature, while they tend to experience a cool feeling when viewing objects in a high color temperature. Therefore, projectors are often provided with a preset, user-selectable, menu for delivering different color temperature to set different visual effects during various operating occasions such as a conference briefing or a movie presentation. Users can select one of the preset values from the menu to adjust the color temperature of the projector.
However, most conventional projectors with such color temperature adjusting capability are only provided with a few preset color temperature values. The color temperature adjustment range is limited by the preset color temperature values. In some circumstances, the preset color temperature is substantially different from user's request. This may lead to colors in images not seeming true to life. Hence, not only the color temperature adjustment range is limited, but also fine adjustment of the color temperature is not possible.
Therefore, it is desired to develop a projector with an adjustable color temperature range for an image of the projector.